JP3120482B2 - Current lead of superconducting magnet device - Google Patents
Current lead of superconducting magnet deviceInfo
- Publication number
- JP3120482B2 JP3120482B2 JP03205321A JP20532191A JP3120482B2 JP 3120482 B2 JP3120482 B2 JP 3120482B2 JP 03205321 A JP03205321 A JP 03205321A JP 20532191 A JP20532191 A JP 20532191A JP 3120482 B2 JP3120482 B2 JP 3120482B2
- Authority
- JP
- Japan
- Prior art keywords
- lead
- temperature side
- heat exchange
- side lead
- current
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
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- Containers, Films, And Cooling For Superconductive Devices (AREA)
Description
【０００１】[0001]
【産業上の利用分野】この発明は、極低温にある超電導
コイルに室温にある電源からの電流を通流する電流リー
ド、ことに低温側リードに酸化物系超電導導体を用いた
電流リードの主に高温側リード側の冷却構造に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current lead for passing a current from a power supply at room temperature to a superconducting coil at a very low temperature, and particularly to a current lead using an oxide superconducting conductor for a low-temperature side lead. And a cooling structure on the high-temperature side lead side.
【０００２】[0002]
【従来の技術】一般に超電導コイルは液体ヘリウム等の
極低温冷媒によって冷却されるため、液体窒素シールド
や高真空などで熱の侵入を阻止した断熱真空容器内に設
けられた液体ヘリウム容器に液体ヘリウムに浸漬した状
態で収納される。電流リードは極低温に保持された超電
導電磁石としての超電導コイルに常温側から励磁電流を
通流するために設けられるものであり、リードで発生す
るジュール熱および常温側から極低温側に伝導により侵
入する熱を低減するために、電流リードの内部に気化し
た低温のヘリウムガスを流すよう構成したものが知られ
ている。この場合、電流リードの材料としては銅または
銅合金のような常電導体を用いるのが一般的であるが、
その熱伝導率が高く侵入熱を低減する効果が期待できな
い。そこで、電流リードを常電導リ−ドと酸化物系超電
導体を用いた超電導リ−ドとの直列接続体とし、中間接
続部に液体窒素容器を設けて超電導リ−ドを液体窒素温
度（７７．３５Ｋ）近傍に保ち、超電導リ−ドを超電導
状態とするよう構成したものが、特開昭６３−２９２６
１０号公報に開示されている。また、液体窒素による冷
却構造を改善したものが、特願平２−２１１３０７号，
特願平３−１０１０６２号に開示されている。2. Description of the Related Art In general, a superconducting coil is cooled by a cryogenic refrigerant such as liquid helium. It is stored in a state of being immersed in. The current lead is provided to allow the excitation current to flow from the room temperature side to the superconducting coil as a superconducting magnet held at a cryogenic temperature, and Joule heat generated at the lead and conduction from the room temperature side to the cryogenic side by conduction. There is known a configuration in which a low-temperature vaporized helium gas is caused to flow into a current lead in order to reduce heat generated. In this case, it is common to use a normal conductor such as copper or a copper alloy as a material for the current lead,
Its thermal conductivity is so high that the effect of reducing the heat of penetration cannot be expected. Therefore, the current lead is a series connection of a normal conducting lead and a superconducting lead using an oxide-based superconductor, and a liquid nitrogen container is provided at an intermediate connecting portion to set the superconducting lead to a temperature of liquid nitrogen (77 ° C.). .35K) and the superconducting lead is brought into a superconducting state.
No. 10 discloses this. An improved cooling structure using liquid nitrogen is disclosed in Japanese Patent Application No. 221307/1990.
It is disclosed in Japanese Patent Application No. 3-101062.
【０００３】図５は従来の超電導磁石装置の電流リード
の冷却構造を模式化して示す断面図である。図におい
て、超電導コイル１は断熱真空容器４の液体ヘリウム容
器２内に液体ヘリウム３に浸漬した状態で収納され、超
電導状態が保持される。電流リード１１は銅等の良導電
性金属導体からなる高温側リード１３と、酸化物系超電
導導体からなる低温側リード１２とが中間接続部１４で
導電接続された直列接続体からなり、低温端子１２Ａが
超電導コイル１に接続され、常温端子１３Ａが図示しな
い電源に接続されることにより、超電導コイル１に電流
が供給される。また、電流リード１１は液体窒素容器１
５を備え、中間接続部１４を含む高温側リード１３が液
体窒素１６中に所定の深さ浸漬されて液体窒素冷却され
るとともに、気化した低温の窒素ガス１６Ｇが外管１７
と高温側リード１３との間に形成された冷却通路１８を
通って上部に排出される過程で高温側リード１３がガス
冷却される。また、低温側リード１２は液体ヘリウム容
器内で気化した低温のヘリウムガス３Ｇによりガス冷却
される。FIG. 5 is a sectional view schematically showing a cooling structure of a current lead of a conventional superconducting magnet device. In the figure, a superconducting coil 1 is accommodated in a liquid helium container 2 of a heat insulating vacuum container 4 in a state of being immersed in liquid helium 3, and the superconducting state is maintained. The current lead 11 is a series connection body in which a high-temperature side lead 13 made of a good conductive metal conductor such as copper and a low-temperature side lead 12 made of an oxide-based superconducting conductor are conductively connected at an intermediate connection portion 14. A current is supplied to the superconducting coil 1 by connecting 12A to the superconducting coil 1 and connecting the room temperature terminal 13A to a power supply (not shown). The current lead 11 is connected to the liquid nitrogen container 1
5, the high-temperature side lead 13 including the intermediate connection portion 14 is immersed in liquid nitrogen 16 to a predetermined depth to be cooled by liquid nitrogen, and the vaporized low-temperature nitrogen gas 16G is
The high-temperature side lead 13 is gas-cooled while being discharged to the upper part through the cooling passage 18 formed between the high-temperature side lead 13 and the high-temperature side lead 13. The low-temperature side lead 12 is gas-cooled by the low-temperature helium gas 3G vaporized in the liquid helium container.
【０００４】[0004]
【発明が解決しようとする課題】上述の電流リードにお
いて、酸化物系超電導導体としてイットリウム（Ｙ），
バリウム（Ｂａ），銅（Ｃｕ），酸素（Ｏ）を含むセラ
ミック系高温超電導体を用いた場合、液体窒素温度以下
で超電導常態を示し、ジュ−ル熱が零になるとともに、
その熱伝導率が銅のそれより２〜３桁も小さく伝導によ
る侵入熱を大幅に低減することができる。従って、高価
な酸化物系超電導導体を用いることにより得られる侵入
熱の低減と、これに伴う液体ヘリウムの消費量の低減効
果を発揮するためには、良導電体であると同時に良熱伝
導体でもある高温側リード１３の熱伝導による侵入熱，
および電流により発生するジュ−ル熱（併せて侵入熱と
呼ぶ）を、液体窒素容器１５中の液体窒素１６が吸収
し、中間接続部１４の温度を液体窒素温度近くに保持す
ることが求められる。ところが、銅棒からなる高温側リ
ードの外周面を液体窒素冷却する従来の冷却方式では、
侵入熱を吸収するに十分な熱交換面積を得られないこと
が多く、かつ十分な熱交換面積を得ようとすると液体窒
素容器が大型化するという問題があり、十分な液体窒素
冷却効果が得られないために低温側リード１２への侵入
熱が大きく、酸化物系超電導導体を超電導状態に維持で
きないという問題があった。In the above-described current lead, yttrium (Y),
When a ceramic-based high-temperature superconductor containing barium (Ba), copper (Cu), and oxygen (O) is used, superconducting normality is exhibited below the temperature of liquid nitrogen, Joule heat is reduced to zero, and
Its thermal conductivity is two to three orders of magnitude lower than that of copper, and the heat penetration due to conduction can be greatly reduced. Therefore, in order to reduce the invasion heat obtained by using an expensive oxide-based superconducting conductor and the effect of reducing the consumption of liquid helium accompanying this, it is necessary to use a good heat conductor as well as a good conductor. However, the heat penetrated by the heat conduction of the high-temperature side lead 13,
It is required that the liquid nitrogen 16 in the liquid nitrogen container 15 absorbs the Joule heat generated by the electric current (hereinafter also referred to as intrusion heat) and keeps the temperature of the intermediate connection portion 14 close to the liquid nitrogen temperature. . However, in the conventional cooling method of cooling the outer peripheral surface of the high-temperature side lead made of a copper rod with liquid nitrogen,
In many cases, it is not possible to obtain a sufficient heat exchange area to absorb invasion heat, and if it is attempted to obtain a sufficient heat exchange area, there is a problem that the liquid nitrogen container becomes large, and a sufficient liquid nitrogen cooling effect is obtained. Therefore, heat penetrating into the low-temperature side lead 12 is large, and there is a problem that the oxide-based superconducting conductor cannot be maintained in a superconducting state.
【０００５】すなわち、電流リード１１の定格電流を１
ｋＡ，高温側リード１３の電流密度を１０Ａ／ｍｍ
2 （銅棒の断面積１００ｍｍ2 ），その長さを５００ｍ
ｍ，その温度差を２２０Ｋとした場合、熱伝導率４００
Ｗ／ｍ−Ｋの銅材からなる高温側リードの伝導熱量Ｑｃ
は１８Ｗとなり、電流の通流により発生するジュ−ル熱
は銅の体積抵抗率を１．１Ω−ｍとすると５５Ｗとな
り、両者の和からなる高温側リードの侵入熱は７３Ｗと
なる。また、高温側リードの下端部５０ｍｍを液体窒素
に浸漬して沸騰冷却する場合、液体窒素冷却面における
熱流束ｑは４１ｋＷ／ｍ2 となる。That is, when the rated current of the current lead 11 is 1
kA, the current density of the high-temperature side lead 13 is 10 A / mm
2 (Cross-sectional area of copper bar 100mm 2 ), length 500m
m, when the temperature difference is 220K, the thermal conductivity is 400
Conduction heat quantity Qc of high-temperature side lead made of W / m-K copper material
Is 18 W, the Joule heat generated by the flow of current is 55 W when the volume resistivity of copper is 1.1 Ω-m, and the heat of penetration of the high-temperature side lead, which is the sum of the two, is 73 W. When the lower end 50 mm of the high-temperature side lead is immersed in liquid nitrogen and cooled by boiling, the heat flux q on the liquid nitrogen cooling surface is 41 kW / m 2 .
【０００６】図６は大気圧における液体窒素の沸騰冷却
特性線図であり、熱流束ｑを４１ｋＷ／ｍ2 とした場
合、核沸騰する液体窒素と高温側リードとの間に７°Ｃ
に近い温度差ΔＴが生ずるため、中間接続部１４におけ
る電流リードの温度は８４Ｋ程度迄しか低下せず、低温
側リード１２の上端部分もこの温度となるため、イット
リウム系超電導導体の臨界電流は臨界温度におけるそれ
の１／２程度に落ちてしまい、高価な酸化物系超電導導
体を用いた効果を十分に発揮できないという問題が発生
する。また、上記効果を発揮させるためには熱流束ｑを
下げる必要があり、高温側リードの断面積の増大や、液
体窒素への浸漬深さの増大など、電流リードの大型化や
液体窒素容器の大型化を招く悪影響が発生する。FIG. 6 is a characteristic diagram of the boiling and cooling characteristics of liquid nitrogen at atmospheric pressure. When the heat flux q is 41 kW / m 2 , the temperature between the nucleate boiling liquid nitrogen and the high-temperature side lead is 7 ° C.
Is generated, the temperature of the current lead at the intermediate connecting portion 14 decreases only to about 84 K, and the upper end portion of the low-temperature side lead 12 also has this temperature. Therefore, the critical current of the yttrium-based superconductor becomes critical. The temperature drops to about half of that at the temperature, and a problem occurs that the effect of using the expensive oxide-based superconductor cannot be sufficiently exhibited. Further, in order to exert the above effect, it is necessary to reduce the heat flux q, and the current lead becomes large, such as an increase in the cross-sectional area of the high-temperature side lead and an increase in the immersion depth in liquid nitrogen, The adverse effect of increasing the size occurs.
【０００７】この発明の目的は、電流リードや液体窒素
容器を大型化することなく液体窒素冷却面積を拡張する
ことにより、低温側リード側への侵入熱を低減すること
にある。An object of the present invention is to reduce the heat entering the low temperature side lead side by expanding the liquid nitrogen cooling area without increasing the size of the current lead or the liquid nitrogen container.
【０００８】[0008]
【課題を解決するための手段】上記課題を解決するため
に、この発明によれば、真空断熱容器内に設けられた液
体ヘリウム容器内に液体ヘリウムに浸漬した状態で収納
された超電導コイルに外部より電流を通流する電流リー
ドが、良導電性金属からなる高温側リードと、酸化物系
超電導導体からなる低温側リードとの直列接続体で構成
されたものにおいて、前記高温側リードと低温側リード
との中間接続部に介装されて両者を導電接続するととも
に液体窒素冷却される熱交換ブロックと、前記高温側リ
ードを前記熱交換ブロック内で気化した低温の窒素ガス
により冷却する冷却通路とを備えてなるものとする。ま
た、前記熱交換ブロックが電流リードの定格電流１ｋＡ
当たり５０cm2 以上の液体窒素冷却される冷却表面積を
保持するよう形成されてなるものとする。According to the present invention, there is provided a superconducting coil housed in a liquid helium container provided in a vacuum heat insulating container while being immersed in liquid helium. A current lead through which more current flows is formed by a series connection of a high-temperature side lead made of a good conductive metal and a low-temperature side lead made of an oxide-based superconducting conductor. A heat exchange block that is interposed at an intermediate connection portion with the lead and conductively connects the two, and is cooled by liquid nitrogen; and a cooling passage that cools the high-temperature side lead by low-temperature nitrogen gas vaporized in the heat exchange block. Shall be provided. In addition, the heat exchange block has a rated current of a current lead of 1 kA.
It is formed so as to maintain a cooling surface area of 50 cm 2 or more per liquid nitrogen cooling.
【０００９】また、熱交換ブロックは、中空に形成され
てその内部に液体窒素室を形成するとともに、この液体
窒素室に連通して高温側リードを包囲する外管により高
温側リードの冷却通路が形成されてなるもの、または、
液体窒素室が熱交換ブロックを覆う外被により中空部の
外部まで拡張されるとともに、外管の下端部が前記外被
に連結されて高温側リードの冷却通路が形成されてなる
ものとする。The heat exchange block is formed hollow to form a liquid nitrogen chamber therein, and a cooling passage for the high temperature side lead is formed by an outer tube communicating with the liquid nitrogen chamber and surrounding the high temperature side lead. Formed, or
The liquid nitrogen chamber is extended to the outside of the hollow portion by a jacket covering the heat exchange block, and the lower end of the outer tube is connected to the jacket to form a cooling passage for the high-temperature side lead.
【００１０】さらに、高温側リードが棒状の良導電性金
属からなり、その外周面に冷却通路に突出した冷却フィ
ンを備えてなるもの、あるいは、高温側リードが外管内
に充填された良導電性金属線の束からなり、熱交換ブロ
ックに分散して導電接続されるとともに、良導電性金属
線の隙間に冷却通路が形成されてなるものとする。Further, the high-temperature side lead is made of a rod-shaped good conductive metal and provided with cooling fins protruding into a cooling passage on the outer peripheral surface thereof, or the high-temperature side lead is filled with a good conductive metal in an outer tube. It is composed of a bundle of metal wires, and is conductively dispersed and connected to the heat exchange block, and has a cooling passage formed in a gap between the highly conductive metal wires.
【００１１】[0011]
【作用】この発明の構成において、良導電性金属からな
る高温側リードと、酸化物系超電導導体からなる低温側
リードとの直列接続体で構成される電流リードに、高温
側リードと低温側リードとの接続部に介装されて両者を
導電接続するとともに液体窒素冷却される熱交換ブロッ
クと、高温側リードを熱交換ブロック内で気化した低温
の窒素ガスにより冷却する冷却通路とを設けるよう構成
したことにより、熱交換ブロックが高温側リードの一部
を兼ね、その形状の決め方により高温側リードの断面積
や熱交換ブロックを大型化することなく液体窒素による
広い冷却面積を確保することに役立つので、冷却面にお
ける熱流束を低減する機能が得られ、中間接続部の温度
を液体窒素温度近くに保持して酸化物系超電導導体から
なる低温側リードを超電導状態に安定して保つことがで
きる。また、熱交換ブロックが電流リードの定格電流１
ｋＡ当たり５０cm2 以上の液体窒素冷却される冷却表面
積を保持するよう形成すれば、核沸騰状態の液体窒素と
の温度差を３Ｋ以下に保持し、高温側リードの侵入熱を
効率よく液体窒素に伝達できる冷却性能を有する電流リ
ードが得られる。In the structure of the present invention, a current lead composed of a series connection of a high-temperature side lead made of a good conductive metal and a low-temperature side lead made of an oxide-based superconductor is connected to a high-temperature side lead and a low-temperature side lead. A heat exchange block interposed at the connection part of the heat exchange block and electrically connected to both, and cooled by liquid nitrogen; and a cooling passage configured to cool the high-temperature side lead by low-temperature nitrogen gas vaporized in the heat exchange block. By doing so, the heat exchange block also serves as a part of the high-temperature side lead, and the shape of the heat exchange block helps secure a large cooling area by liquid nitrogen without increasing the cross-sectional area of the high-temperature side lead and the heat exchange block in size. Therefore, a function to reduce the heat flux on the cooling surface is obtained, and the temperature of the intermediate connection portion is kept close to the temperature of liquid nitrogen, and the low-temperature side lead made of an oxide-based superconducting conductor is provided. It can be kept stable in the superconducting state. In addition, the heat exchange block is rated current 1 of the current lead.
If it is formed so as to maintain a cooling surface area of 50 cm 2 or more per kA of liquid nitrogen cooling, the temperature difference with liquid nitrogen in a nucleate boiling state is maintained at 3 K or less, and the heat entering the high-temperature side lead is efficiently converted into liquid nitrogen. A current lead having a transferable cooling performance is obtained.
【００１２】また、熱交換ブロックを中空に形成してそ
の内部に液体窒素室を形成するとともに、この液体窒素
室に連通して高温側リードを包囲する外管により高温側
リードの冷却通路を形成すれば、熱交換ブロックが液体
窒素容器を兼ね、その内壁面を熱交換面として高温側リ
ードの侵入熱を排熱でき、かつ気化した窒素ガスで高温
側リードをガス冷却することができる。また、熱交換ブ
ロックに外被を設けて液体窒素室を中空部の外部まで拡
張すれば、より広い冷却表面積を確保して熱流束を低減
し、中間接続部の温度を液体窒素温度近くに保持して低
温側リードへの侵入熱を低減する機能が得られる。Further, the heat exchange block is formed hollow to form a liquid nitrogen chamber therein, and a cooling passage for the high temperature side lead is formed by an outer tube communicating with the liquid nitrogen chamber and surrounding the high temperature side lead. Then, the heat exchange block also serves as a liquid nitrogen container, the inner wall surface of the heat exchange block can be used as a heat exchange surface, and the heat of invasion of the high-temperature side lead can be exhausted, and the high-temperature side lead can be gas-cooled with the vaporized nitrogen gas. In addition, if the liquid nitrogen chamber is extended to the outside of the hollow part by providing a jacket on the heat exchange block, a larger cooling surface area is secured, the heat flux is reduced, and the temperature of the intermediate connection part is maintained near the liquid nitrogen temperature As a result, a function of reducing heat penetrating into the low-temperature side lead is obtained.
【００１３】さらに、高温側リードが棒状の良導電性金
属からなり、その外周面に冷却通路に突出した冷却フィ
ンを設ければ、高温側リードのガス冷却性能の向上によ
り、熱交換ブロック側への侵入熱量を低減する機能が得
られる。また、高温側リードを外管内に挿入された良導
電性金属線の束で構成し、その端末を液体窒素室内で熱
交換ブロックに分散して導電接続するとともに、良導電
性金属線相互の隙間を冷却通路とすれば、高温側リード
と液体窒素，窒素ガスとの接触面積を大幅に拡張し、効
率の高いガス冷却を行うことができる。Further, if the high-temperature side lead is made of a rod-shaped good conductive metal and provided with cooling fins protruding into the cooling passage on the outer peripheral surface thereof, the gas cooling performance of the high-temperature side lead is improved and the high-temperature side lead is moved toward the heat exchange block. And a function of reducing the amount of heat that enters. The high-temperature side lead is composed of a bundle of good conductive metal wires inserted into the outer tube, and the terminals are dispersed and connected to the heat exchange block in the liquid nitrogen chamber, and the gap between the good conductive metal wires is formed. If the cooling passage is used, the contact area between the high-temperature side lead and the liquid nitrogen or nitrogen gas can be greatly expanded, and highly efficient gas cooling can be performed.
【００１４】[0014]
【実施例】以下、この発明を実施例に基づいて説明す
る。図１はこの発明の実施例になる超電導磁石装置の電
流リードを示す断面図であり、従来技術と同じ構成部分
には同一参照符号を付すことにより、重複した説明を省
略する。図において、２２は厚肉の銅材からなる中空の
熱交換ブロックであり、その中空部に供給口２２Ａを介
して液体窒素１６を供給することにより、中空部は液体
窒素室２３として利用される。また、熱交換ブロック２
２の下面側の中間接続部２４Ｂには酸化物系超電導導体
の例えばバルク焼結体からなる低温側リード１２が導電
接続され、上面側の中間接続部２４Ａには銅棒等の良導
電性金属で構成される高温側リード１３の下端部が導電
接続されるとともに、高温側リードを同心状に包囲して
高温側リードとの間に冷却通路２７を画成する外管２５
の下端部が気密に結合され、熱交換ブロックで気化した
低温の窒素ガス１６Ｇが冷却通路２７を通って排出口２
５Ａから外部に排出される。さらに、高温側リード１３
はその外周面から冷却通路にスパイラル状に突出した冷
却フィン２６を備え、冷却通路での高温側リードのガス
冷却性能を向上するよう構成される。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments. FIG. 1 is a cross-sectional view showing a current lead of a superconducting magnet device according to an embodiment of the present invention. In the drawing, reference numeral 22 denotes a hollow heat exchange block made of a thick copper material. The hollow portion is used as a liquid nitrogen chamber 23 by supplying liquid nitrogen 16 to the hollow portion through a supply port 22A. . In addition, heat exchange block 2
The low-temperature side lead 12 made of, for example, a bulk sintered body of an oxide-based superconducting conductor is conductively connected to the lower surface side intermediate connection portion 24B, and a good conductive metal such as a copper rod is connected to the upper surface side intermediate connection portion 24A. The lower end of the high-temperature side lead 13 is electrically conductively connected, and the outer tube 25 concentrically surrounds the high-temperature side lead and defines a cooling passage 27 with the high-temperature side lead.
The lower end of the nitrogen gas is hermetically connected, and the low-temperature nitrogen gas 16G vaporized by the heat exchange block passes through the cooling passage 27 and is discharged from the outlet 2
It is discharged from 5A to the outside. Furthermore, the high-temperature side lead 13
Are provided with cooling fins 26 projecting spirally from the outer peripheral surface thereof into the cooling passage, so as to improve the gas cooling performance of the high-temperature side lead in the cooling passage.
【００１５】上述のように構成された実施例になる電流
リード２１においては、熱交換ブロック２２が高温側リ
ードの一部としての電流通路の機能と、液体窒素容器と
しての機能とを兼ね、その液体窒素室２３の内壁面が液
体窒素による核沸騰冷却の熱交換面として機能する。そ
こで、熱交換ブロックの液体窒素による冷却表面積を１
３０ｃｍ2 とし、高温側リードの侵入熱を前述の従来例
と同じ７３Ｗと仮定する。この条件での熱流束は５．６
ｋＷ／ｍ2 となり、核沸騰する液体窒素との温度差ΔＴ
を図６から求めると約３Ｋとなり、中間接続部２４Ｂに
おける熱交換ブロックの温度，言い換えれば低温側リー
ドの上端部の温度を８０Ｋ程度に迄下げることができ、
低温側リード１２の酸化物系超電導導体の臨界電流の低
下を抑制できるとともに、液体窒素室の液深を５ｃｍと
した場合、熱交換ブロックを内径５７ｍｍ程度の円筒形
とすることで必要な冷却表面積を確保できるので、小型
な熱交換ブロックにより低温側リードへの侵入熱量の小
さい電流リードを得ることができる。In the current lead 21 according to the embodiment configured as described above, the heat exchange block 22 has both the function of the current passage as a part of the high-temperature side lead and the function of the liquid nitrogen container. The inner wall surface of the liquid nitrogen chamber 23 functions as a heat exchange surface for nucleate boiling cooling by liquid nitrogen. Therefore, the cooling surface area of the heat exchange block by liquid nitrogen is reduced to 1
It is assumed that the temperature is 30 cm 2 and the heat penetration of the high-temperature side lead is 73 W, which is the same as that of the above-mentioned conventional example. The heat flux under this condition is 5.6
kW / m 2 , the temperature difference ΔT from the nucleate boiling liquid nitrogen
6 is about 3K, and the temperature of the heat exchange block at the intermediate connection portion 24B, in other words, the temperature of the upper end of the low-temperature side lead can be reduced to about 80K.
A reduction in the critical current of the oxide-based superconducting conductor of the low-temperature side lead 12 can be suppressed, and when the liquid depth of the liquid nitrogen chamber is 5 cm, the cooling surface area required by forming the heat exchange block into a cylindrical shape with an inner diameter of about 57 mm is required. Therefore, it is possible to obtain a current lead having a small amount of heat penetrating into the low-temperature side lead by using a small heat exchange block.
【００１６】また、冷却フィンを有する高温側リードの
ガス冷却効果を考慮すると、熱交換ブロックで気化した
液体窒素の自己充足流量（液体窒素の蒸発量０．１２５
ｇ／ｓ）において高温側リードの侵入熱量を２５Ｗ程度
に低減できる。したがって、熱交換ブロックの冷却表面
積を１３０ｃｍ2 に保てば、温度差ΔＴを２°Ｃ以下に
抑制して酸化物系超電導導体の臨界電流の低下をさらに
縮小できる。また、熱流束ｑを５ｋＷ／ｍ2 以下に抑え
れば液体窒素との温度差を３°Ｃ以下とすることができ
る。さらに、電流リードの定格電流が異なっても、電流
リードの寸法を最適化すれば通電電流当たりの侵入熱を
２５Ｗ／ｋＡに保持できるので、熱交換ブロックの冷却
表面積を５０ｃｍ2 以上とすることにより、低温側リー
ド上端部の温度を８０Ｋ以下に保って液体ヘリウム損失
の少ない電流リードを得ることができる。Considering the gas cooling effect of the high-temperature side lead having the cooling fins, the self-sufficient flow rate of the liquid nitrogen vaporized by the heat exchange block (the liquid nitrogen evaporation rate of 0.125
g / s), the amount of heat entering the high-temperature side lead can be reduced to about 25 W. Therefore, if the cooling surface area of the heat exchange block is kept at 130 cm 2 , the temperature difference ΔT is suppressed to 2 ° C. or less, and the decrease in the critical current of the oxide superconductor can be further reduced. Further, if the heat flux q is suppressed to 5 kW / m 2 or less, the temperature difference from liquid nitrogen can be reduced to 3 ° C. or less. Furthermore, even if the rated currents of the current leads are different, if the dimensions of the current leads are optimized, the infiltrated heat per conduction current can be maintained at 25 W / kA. Therefore, by setting the cooling surface area of the heat exchange block to 50 cm 2 or more. By keeping the temperature of the upper end of the low-temperature side lead at 80 K or less, a current lead with little liquid helium loss can be obtained.
【００１７】図２はこの発明の異なる実施例になる電流
リードを示す断面図であり、中空部に複数の貫通孔３４
を有する熱交換ブロック３２が、液体窒素の供給口２２
Ａを有する外被３５に覆われ、液体窒素室３３が中空部
の内外に拡張されるとともに、高温側リード１３を同心
状に覆う外管２５の下端部が外被に連結され、液体窒素
室で気化した低温の窒素ガスによる冷却通路２７を形成
するよう構成された点が前述の実施例と異なっている。
このように構成された電流リード３１においては、熱交
換ブロック３２の表面を液体窒素の核沸騰に寄与する冷
却面として活用できるので、高温側リードの侵入熱をよ
り高度に排除して低温側リード１２の酸化物系超電導導
体を超電導常態に安定して保持できるとともに、電流リ
ード３１の定格電流の増大に対して熱交換ブロックを大
型化することなく、侵入熱を排熱できる利点が得られ
る。FIG. 2 is a sectional view showing a current lead according to a different embodiment of the present invention.
The heat exchange block 32 having the liquid nitrogen supply port 22
A, the liquid nitrogen chamber 33 is extended inside and outside the hollow portion, and the lower end of an outer tube 25 concentrically covering the high-temperature side lead 13 is connected to the outer cover, and the liquid nitrogen chamber is covered with the liquid nitrogen chamber. This embodiment is different from the above-described embodiment in that the cooling passage 27 is formed by a low-temperature nitrogen gas vaporized in the above.
In the current lead 31 configured as described above, the surface of the heat exchange block 32 can be used as a cooling surface that contributes to the nucleate boiling of liquid nitrogen. Twelve oxide-based superconducting conductors can be stably maintained in a superconducting normal state, and the advantage of being able to exhaust intrusion heat without increasing the size of the heat exchange block with respect to an increase in the rated current of the current lead 31 is obtained.
【００１８】図３はこの発明の他の実施例になる電流リ
ードの要部を示す断面図、図４は図３におけるＡ−Ａ位
置の断面図である。図において、高温側リード４３は丸
銅線４５の束として外管２５内に挿入され、その下端部
分は複数組に分割されて熱交換ブロック４２に導電接続
されて高温側リードと熱交換ブロックの中間接続部４４
を形成する。このように構成された電流リード４１にお
いては、液体窒素１６中に浸漬された高温側リードの端
末部分が広い冷却表面積を持ち、液体窒素による侵入熱
の排熱が容易化されるとともに、丸銅線４５相互の隙間
で構成される冷却通路４７のガス冷却表面積が大きく、
この部分での熱交換も活性化されるので、低温側リード
１２の上端部分の温度を液体窒素温度により近づけるこ
とができ、したがって高価な液体ヘリウムの気化損失が
極めて少ない電流リードを備えた超電導磁石装置を得る
ことができる。FIG. 3 is a sectional view showing a main part of a current lead according to another embodiment of the present invention, and FIG. 4 is a sectional view taken along a line AA in FIG. In the figure, the high-temperature side lead 43 is inserted into the outer tube 25 as a bundle of round copper wires 45, and the lower end portion is divided into a plurality of sets and is conductively connected to the heat exchange block 42 to connect the high-temperature side lead and the heat exchange block. Intermediate connector 44
To form In the current lead 41 configured as described above, the terminal portion of the high-temperature side lead immersed in the liquid nitrogen 16 has a large cooling surface area, thereby facilitating the discharge of the intrusion heat by the liquid nitrogen and the round copper. The gas cooling surface area of the cooling passage 47 formed by the gap between the lines 45 is large,
Since the heat exchange in this portion is also activated, the temperature of the upper end portion of the low-temperature side lead 12 can be brought closer to the temperature of liquid nitrogen, and therefore, a superconducting magnet provided with a current lead that has extremely low vaporization loss of expensive liquid helium. A device can be obtained.
【００１９】[0019]
【発明の効果】この発明は前述のように、良導電性金属
からなる高温側リードと、酸化物系超電導導体からなる
低温側リードとの直列接続体で構成される電流リード
に、高温側リードと低温側リードとの接続部に介装され
て両者を導電接続するとともに液体窒素冷却される熱交
換ブロックと、高温側リードを熱交換ブロック内で気化
した低温の窒素ガスにより冷却する冷却通路とを設ける
よう構成した。その結果、熱交換ブロックが高温側リー
ドの一部を兼ね、その形状の決め方により高温側リード
の断面積や熱交換ブロックを大型化することなく液体窒
素による広い冷却表面積を確保することに役立つので、
従来技術での問題点が排除され、冷却面における熱流束
を低減し、中間接続部の温度を液体窒素温度近くに保持
して酸化物系超電導導体からなる低温側リードを超電導
常態に安定して維持し、高価な液体ヘリウムの消費量の
少ない電流リードを備えた超電導磁石装置を提供するこ
とができる。また、熱交換ブロックが電流リードの定格
電流１ｋＡ当たり５０cm2 以上の液体窒素冷却される冷
却表面積を保持するよう形成すれば、核沸騰状態の液体
窒素との温度差を３Ｋ以下に保持し、酸化物系超電導導
体の臨界電流の低下を抑制できる電流リードを備えた超
電導磁石装置を提供することができる。As described above, the present invention relates to a current lead comprising a series connection of a high-temperature side lead made of a good conductive metal and a low-temperature side lead made of an oxide-based superconducting conductor. A heat exchange block interposed at a connection portion between the heat exchange block and the low-temperature side lead and electrically connected to each other and cooled by liquid nitrogen; and a cooling passage for cooling the high-temperature side lead by low-temperature nitrogen gas vaporized in the heat exchange block. Was provided. As a result, the heat exchange block also serves as a part of the high-temperature side lead, and the shape of the heat exchange block helps secure a large cooling surface area by liquid nitrogen without increasing the cross-sectional area of the high-temperature side lead or the heat exchange block. ,
The problems with the conventional technology are eliminated, the heat flux on the cooling surface is reduced, the temperature of the intermediate connection is kept close to the temperature of liquid nitrogen, and the low-temperature side lead made of an oxide-based superconducting conductor is stably maintained in a superconducting normal state. It is possible to provide a superconducting magnet device having a current lead that maintains and consumes less expensive liquid helium. Further, if the heat exchange block is formed so as to maintain a cooling surface area for cooling liquid nitrogen of 50 cm 2 or more per 1 kA of rated current of the current lead, the temperature difference with liquid nitrogen in a nucleate boiling state is maintained at 3 K or less, and oxidation is performed. It is possible to provide a superconducting magnet device including a current lead capable of suppressing a decrease in critical current of a material-based superconducting conductor.
【００２０】また、熱交換ブロックを中空に形成してそ
の内部に液体窒素室を形成するとともに、この液体窒素
室に連通して高温側リードを包囲する外管により高温側
リードの冷却通路を形成すれば、熱交換ブロックが液体
窒素容器を兼ね、その内壁面を熱交換面として高温側リ
ードの侵入熱を排熱でき、かつ気化した窒素ガスで高温
側リードをガス冷却することができるので、小型化した
熱交換ブロックを用いて酸化物系超電導導体を安定して
超電導常態に維持できる電流リードが得られる。また、
熱交換ブロックに外被を設けて液体窒素室を中空部の外
部まで拡張すれば、より広い熱交換面積を確保して高温
側リードの侵入熱を排除できる電流リードを提供するこ
とができる。Further, the heat exchange block is formed hollow to form a liquid nitrogen chamber therein, and a cooling passage for the high temperature side lead is formed by an outer tube communicating with the liquid nitrogen chamber and surrounding the high temperature side lead. If this is done, the heat exchange block also serves as a liquid nitrogen container, the inner wall surface of which can be used as a heat exchange surface to remove the heat of penetration of the high-temperature side lead, and to cool the high-temperature side lead with gasified nitrogen gas. A current lead that can stably maintain an oxide-based superconducting conductor in a superconducting normal state using a miniaturized heat exchange block can be obtained. Also,
If the heat exchange block is provided with a jacket and the liquid nitrogen chamber is extended to the outside of the hollow portion, it is possible to provide a current lead that can secure a wider heat exchange area and eliminate heat entering the high-temperature side lead.
【００２１】さらに、高温側リードが棒状の良導電性金
属からなり、その外周面に冷却通路に突出した冷却フィ
ンを設ければ、高温側リードのガス冷却性能の向上によ
り、高温側リードの侵入熱を従来の１／２以下に低減で
きるので、より高い冷却性能を有する電流リードを提供
することができる。また、高温側リードを外管内に挿入
された良導電性金属線の束で構成し、良導電性金属線の
隙間を冷却通路とすれば、液体窒素および窒素ガスとの
冷却表面積を大幅に拡張でき、熱交換ブロックの温度を
液体窒素の臨界温度に一層近づけ、酸化物系超電導導体
の臨界電流の低下を阻止できる電流リードを備えた超電
導磁石装置を提供することができる。Further, if the high-temperature side lead is made of a rod-shaped good conductive metal and provided with cooling fins protruding into the cooling passage on its outer peripheral surface, the gas cooling performance of the high-temperature side lead is improved, so that the high-temperature side lead can be intruded. Since the heat can be reduced to half or less of that of the related art, a current lead having higher cooling performance can be provided. In addition, if the high-temperature side lead is composed of a bundle of good conductive metal wires inserted into the outer tube, and the gap between the good conductive metal wires is used as a cooling passage, the cooling surface area for liquid nitrogen and nitrogen gas is greatly expanded. Thus, it is possible to provide a superconducting magnet device provided with a current lead that can bring the temperature of the heat exchange block closer to the critical temperature of liquid nitrogen and prevent a decrease in the critical current of the oxide superconducting conductor.
【図１】この発明の実施例になる超電導磁石装置の電流
リードを示す断面図FIG. 1 is a sectional view showing a current lead of a superconducting magnet device according to an embodiment of the present invention.
【図２】この発明の異なる実施例になる電流リードを示
す断面図FIG. 2 is a sectional view showing a current lead according to a different embodiment of the present invention;
【図３】この発明の他の実施例になる電流リードの要部
を示す断面図FIG. 3 is a sectional view showing a main part of a current lead according to another embodiment of the present invention;
【図４】図３におけるＡ−Ａ位置の断面図FIG. 4 is a sectional view taken along a line AA in FIG. 3;
【図５】従来の超電導磁石装置の電流リードの冷却構造
を模式化して示す断面図FIG. 5 is a cross-sectional view schematically illustrating a cooling structure of a current lead of a conventional superconducting magnet device.
【図６】大気圧における液体窒素の沸騰冷却特性線図FIG. 6 is a characteristic diagram of boiling and cooling characteristics of liquid nitrogen at atmospheric pressure.
１ 超電導コイル ２ 液体ヘリウム容器 ３ 液体ヘリウム ４ 真空断熱容器 １１ 電流リード １２ 低温側リード（酸化物系超電導導体） １３ 高温側リード（良導電性金属導体） １４ 中間接続部 １５ 液体窒素容器 １６ 液体窒素 １６Ｇ 窒素ガス １７ 外管 １８ 冷却通路 ２１ 電流リード ２２ 熱交換ブロック ２３ 液体窒素室 ２４ 中間接続部 ２６ 冷却フィン ２７ 冷却通路 ３１ 電流リード ３２ 熱交換ブロック ３３ 液体窒素室 ３４ 貫通孔 ３５ 外被 ４１ 電流リード ４２ 熱交換ブロック ４３ 高温側リード ４４ 接続部 ４５ 銅線 ４７ 冷却通路 ｑ 液体窒素冷却面の熱流束 ΔＴ 液体窒素との温度差 DESCRIPTION OF SYMBOLS 1 Superconducting coil 2 Liquid helium container 3 Liquid helium 4 Vacuum insulated container 11 Current lead 12 Low temperature side lead (oxide superconducting conductor) 13 High temperature side lead (good conductive metal conductor) 14 Intermediate connection part 15 Liquid nitrogen container 16 Liquid nitrogen 16G Nitrogen gas 17 Outer tube 18 Cooling passage 21 Current lead 22 Heat exchange block 23 Liquid nitrogen chamber 24 Intermediate connection part 26 Cooling fin 27 Cooling passage 31 Current lead 32 Heat exchange block 33 Liquid nitrogen chamber 34 Through hole 35 Jacket 41 Current lead 42 heat exchange block 43 high temperature side lead 44 connection part 45 copper wire 47 cooling passage q heat flux of liquid nitrogen cooling surface ΔT temperature difference from liquid nitrogen
フロントページの続き (56)参考文献 特開 昭63−299217（ＪＰ，Ａ) 特開 昭63−292610（ＪＰ，Ａ) 特開 昭62−25473（ＪＰ，Ａ) 特開 平４−94105（ＪＰ，Ａ) 特開 平４−332105（ＪＰ，Ａ) (58)調査した分野(Int.Cl.7，ＤＢ名) H01L 39/02 - 39/04 H01L 39/14 - 39/16 H01L 39/20 H01F 6/00 Continuation of the front page (56) References JP-A-63-299217 (JP, A) JP-A-63-292610 (JP, A) JP-A-62-25473 (JP, A) JP-A-4-94105 (JP) , A) JP-A-4-332105 (JP, A) (58) Fields investigated (Int. Cl. 7 , DB name) H01L 39/02-39/04 H01L 39/14-39/16 H01L 39/20 H01F 6/00
Claims (6)
容器内に液体ヘリウムに浸漬した状態で収納された超電
導コイルに外部より電流を通流する電流リードが、良導
電性金属からなる高温側リードと、酸化物系超電導導体
からなる低温側リードとの直列接続体で構成されたもの
において、前記高温側リードと低温側リードとの中間接
続部に介装されて両者を導電接続するとともに液体窒素
冷却される熱交換ブロックと、前記高温側リードを前記
熱交換ブロック内で気化した低温の窒素ガスにより冷却
する冷却通路とを備えてなることを特徴とする超電導磁
石装置の電流リード。A current lead for passing a current from the outside to a superconducting coil housed in a liquid helium container provided in a vacuum insulated container while being immersed in liquid helium is provided on a high-temperature side made of a highly conductive metal. A series connection body of a lead and a low-temperature side lead made of an oxide-based superconducting conductor, interposed at an intermediate connecting portion between the high-temperature side lead and the low-temperature side lead to electrically connect the two and electrically connect the two. A current lead for a superconducting magnet device, comprising: a heat exchange block that is cooled by nitrogen; and a cooling passage that cools the high-temperature side lead with a low-temperature nitrogen gas vaporized in the heat exchange block.
ｋＡ当たり５０cm2以上の液体窒素冷却される冷却表面
積を保持するよう形成されてなることを特徴とする請求
項１に記載の超電導磁石装置の電流リード。2. The heat exchange block has a rated current of a current lead of 1.
2. The current lead for a superconducting magnet device according to claim 1, wherein the current lead is formed so as to maintain a cooling surface area cooled by liquid nitrogen of 50 cm 2 or more per kA.
部に液体窒素室を形成するとともに、この液体窒素室に
連通して高温側リードを包囲する外管により高温側リー
ドの冷却通路が形成されてなることを特徴とする請求項
１または請求項２のいずれかに記載の超電導磁石装置の
電流リード。3. A heat exchange block is formed hollow to form a liquid nitrogen chamber therein, and a cooling passage for the high temperature side lead is formed by an outer tube communicating with the liquid nitrogen chamber and surrounding the high temperature side lead. The current lead of the superconducting magnet device according to claim 1, wherein the current lead is provided.
より中空部の外部まで拡張されるとともに、外管の下端
部が前記外被に連結されて高温側リードの冷却通路が形
成されてなることを特徴とする請求項３に記載の超電導
磁石装置の電流リード。4. A liquid nitrogen chamber is extended to the outside of the hollow portion by a jacket covering the heat exchange block, and a lower end of the outer tube is connected to the jacket to form a cooling passage for a high-temperature side lead. The current lead of the superconducting magnet device according to claim 3, wherein
り、その外周面に冷却通路に突出した冷却フィンを備え
てなることを特徴とする請求項３または請求項４のいず
れかに記載の超電導磁石装置の電流リード。5. The high-temperature side lead is made of a rod-shaped good conductive metal, and is provided with cooling fins protruding into a cooling passage on an outer peripheral surface thereof. Current lead of superconducting magnet device.
性金属線の束からなり、熱交換ブロックに分散して導電
接続されるとともに、良導電性金属線の隙間に冷却通路
が形成されてなることを特徴とする請求項３または請求
項４のいずれかに記載の超電導磁石装置の電流リード。6. A high-temperature side lead is formed of a bundle of good conductive metal wires inserted into an outer tube, and is dispersed and connected to a heat exchange block, and a cooling passage is formed in a gap between the good conductive metal wires. The current lead of the superconducting magnet device according to claim 3, wherein the current lead is provided.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03205321A JP3120482B2 (en) | 1991-08-16 | 1991-08-16 | Current lead of superconducting magnet device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP03205321A JP3120482B2 (en) | 1991-08-16 | 1991-08-16 | Current lead of superconducting magnet device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0548156A JPH0548156A (en) | 1993-02-26 |
| JP3120482B2 true JP3120482B2 (en) | 2000-12-25 |
Family
ID=16505011
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP03205321A Expired - Fee Related JP3120482B2 (en) | 1991-08-16 | 1991-08-16 | Current lead of superconducting magnet device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3120482B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103616623A (en) * | 2013-11-28 | 2014-03-05 | 上海三原电缆附件有限公司 | Superconductive terminal current lead testing device |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR101356642B1 (en) * | 2011-10-11 | 2014-02-03 | 삼성전자주식회사 | Superconductive electromagnet device |
| KR101356641B1 (en) | 2011-10-11 | 2014-02-03 | 삼성전자주식회사 | Superconductive electromagnet device |
| CN107978414B (en) * | 2018-01-11 | 2024-06-04 | 合肥中科离子医学技术装备有限公司 | Helium gas channel structure for connecting liquid helium temperature zone and normal temperature zone |
-
1991
- 1991-08-16 JP JP03205321A patent/JP3120482B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103616623A (en) * | 2013-11-28 | 2014-03-05 | 上海三原电缆附件有限公司 | Superconductive terminal current lead testing device |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH0548156A (en) | 1993-02-26 |
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